Posttraumatic tremor without parkinsonism in a patient with complete contralateral loss of the nigrostriatal pathway

Movement disorders secondary to craniocerebral trauma

Over the past few decades it has been recognized that traumatic brain injury may result in various movement disorders. In survivors of severe head injury, post-traumatic movement disorders were reported in about 20%, and they persisted in about 10% of patients. The most frequent persisting movement disorder in this population is kinetic cerebellar outflow tremor in about 9%, followed by dystonia in about 4%. While tremor is associated most frequently with cerebellar or mesencephalic lesions, patients with dystonia frequently have basal ganglia or thalamic lesions. Moderate or mild traumatic brain injury only rarely causes persistent post-traumatic movement disorders. It appears that the frequency of post-traumatic movement disorders overall has been declining which most likely is secondary to improved treatment of brain injury. In patients with disabling post-traumatic movement disorders which are refractory to medical treatment, stereotactic neurosurgery can provide long-lasting benefit. While in the past the primary option for severe kinetic tremor was thalamotomy and for dystonia thalamotomy or pallidotomy, today deep brain stimulation has become the preferred treatment. Parkinsonism is a rare consequence of single head injury, but repeated head injury such as seen in boxing can result in chronic encephalopathy with parkinsonian features. While there is still controversy whether or not head injury is a risk factor for the development of Parkinson's disease, recent studies indicate that genetic susceptibility might be relevant.

Unilateral Holmes tremor, clearly responsive to cerebrospinal fluid release, in a patient with an ischemic midbrain lesion and associated chronic hydrocephalic ventricle enlargement. Case report

The authors describe a 58-year-old man with sudden onset of a unilateral tremor caused by a midbrain lesion that affected the substantia nigra and the cerebellothalamic pathway. There were also clinical and neuroimaging signs of a communicating chronic hydrocephalus. The patient was severely handicapped by this tremor, which was a typical Holmes tremor with rest, posture, and intention components. Parkinson disease or multiple-system atrophy as causes for the tremor could be ruled out by DaTSCAN and 123I iodobenzamide and single-photon emission computerized tomography (SPECT), respectively. The tremor was completely supressed by temporary and permanent cerebrospinal fluid release after ventriculoperitoneal shunt placement, without any additional medication, for a period of 6 months. Afterward, the tremor returned, and the patient had to be treated by a stereotactic electrode implantation in the contralateral ventralis intermedius nucleus, which led to complete tremor suppression during the 1.5-year follow-up period. In this case report, the authors present the clinical description and the electrophysiological, SPECT, and magnetic resonance imaging data of a rare combination of symptoms and their surgical treatment.

Levodopa treatment for patients in persistent vegetative or minimally conscious states

The persistent vegetative state (PVS) and the minimally conscious state (MCS) are conditions of altered consciousness after severe brain damage due to a variety of pathologies. However, the specific pathophysiological mechanisms and a therapeutic strategy for intervention have not as yet been established. We review previous reports of levodopa treatment for patients in PVS, MCS, or other mental disorders, and have focused on five representative cases: four of PVS and one of MCS after severe brain injury. In summary, our review suggests the effectiveness of levodopa treatment is probably dependent upon the following criteria: (1) Diagnosis of PVS or MCS as distinct from other related conditions, (2) Concomitant symptoms of parkinsonism, and (3) Concomitant neuroradiological findings of high intensity lesions in the dopaminergic pathway on T2 weighted MRI. The apparent success of levodopa in the five cases described may reflect a specific subgroup of PVS and MCS patients, where the administration of levodopa is effective. However, we should not regard PVS or MCS as a single entity, since levodopa is unlikely to be effective in all cases. Therapeutic strategies should aim to identify the key pathophysiological mechanism for each patient and target interventions accordingly.